1. Field of the Invention
The present invention generally relates to semiconductor device substrates (substrates for semiconductor devices) and manufacturing methods thereof, and more particularly, to a semiconductor device substrate including a substrate body having a wiring layer, and a base supporting the substrate body and having an opening at a position where a semiconductor device is mounted, and to a manufacturing method of the semiconductor device substrate.
2. Description of the Related Art
Recently, with the increase in the operating frequency of semiconductor elements mounted on semiconductor devices, it becomes necessary to stabilize a power supply voltage supplied to the semiconductor element. In order to meet such a need, there is proposed a structure in which a capacitor element is provided in a semiconductor device substrate (substrate for a semiconductor device) on which a semiconductor element is mounted (refer to Japanese Laid-Open Patent Application No. 2001-274034, for example).
FIG. 1 shows a conventional semiconductor device 1 having a capacitor element and a semiconductor device substrate 3 (hereinafter simply referred to as a “substrate 3”). In the semiconductor device 1, a semiconductor element 2 is mounted in an opening 9 formed in the substrate 3.
The substrate 3 is constructed by a substrate body 5, a base 6, a circuit board 7, and the like. The substrate body 5 is formed on a surface of the base 6 by a build-up method. Vias 8 are formed in the substrate body 5, which is formed by an insulating resin member 16, such that the vias 8 penetrate the substrate body 5 in the longitudinal direction of FIG. 1.
The base 6 is provided for supporting the substrate body 5. Hence, the base 6 is formed by a metal (copper, for example) having a greater mechanical strength than that of the substrate body 5. The opening 9 is formed at a device mounting position of the base 6 where the semiconductor element 2 is mounted.
The circuit board 7 is mounted on the substrate body 5 with a part of the circuit board 7 embedded therein. The circuit board 7 is constructed by a silicon core 10 and a capacitor forming part 12 formed on the top surface of the silicon core 10. Core penetration vias 14, which penetrate the silicon core 10, are formed under the capacitor forming part 12. Bumps 13 for making connection with the semiconductor element 2 are formed on the capacitor forming part 12.
The semiconductor element 2 is flip-chip bonded to the bumps 13 via solder bumps 4. The core penetration vias 14 are connected with the vias 8 formed in the substrate body 5. Consequently, the capacitor forming part 12 is positioned between the semiconductor element 2 and the vias 8 (vias for power supply/grounding). With the capacitor element formed in the capacitor forming part 12, it is possible to stabilize power supply voltage supplied to the semiconductor element 2.
FIGS. 2A, 2B, and 2C show a conventional manufacturing method of the substrate 3. When manufacturing the substrate 3, the circuit board 7 is manufactured in advance in which circuit board 7 the capacitor forming part 12, the bumps 13, and the core penetration vias 14 are formed on the silicon core 10. As shown in FIG. 2A, the circuit board 7 is provided on the base 6 in which the opening 9 is not formed. On this occasion, the circuit board 7 is fixed to the base 6 by using an adhesive material 15.
Subsequently, as shown in FIG. 2, the substrate body 5 is formed by stacking the vias 8, a wiring pattern (not shown), and the insulating resin member 16 by using a build-up method. As a result, the circuit board 7 is embedded in the substrate body 5.
Then, as shown in FIG. 2C, the opening 9 is formed in the base 6 at the mounting position of the semiconductor element 2. The region where the opening 9 is formed is set such that the region where the circuit board 7 is formed is included therein. That is, the size of the opening 9 is set larger than that of the circuit board 7.
As mentioned above, by forming the opening 9 in the base 6, the bumps 13 of the circuit board 7 are exposed. Accordingly, it becomes possible to mount the semiconductor element 2 on the substrate 3.
As mentioned above, the substrate body 5 constituting a part of the substrate 3 is formed mainly by resin. On the other hand, the base 6 is formed by a metal such as cooper. Accordingly, due to the difference in thermal expansion coefficients between the substrate body 5 and the base 6, stress is generated between the substrate body 5 and the base 6 in a heating process (heating for solidifying the adhesive material 15) performed when arranging the circuit board 7 on the base 6 via the adhesive material 15, and in another heating process (heating for forming the insulating resin member 16) performed when forming the substrate body 5.
Before the opening 9 is formed in the base 6, the substrate body 5 is supported by the base 6. Hence, the substrate 3 is not deformed by the stress generated between the substrate body 5 and the base 6. However, as shown in FIG. 2C, when the opening 9 is formed in the base 6, the substrate body 5 is not supported by the base 6 at the portion where the opening 9 is formed. Hence, the substrate body 5 is deformed by the above-mentioned stress.
When the substrate body 5 is deformed as mentioned above, since the size of the circuit board 7 is conventionally smaller than that of the opening 9, the circuit board 7 is shifted from a predetermined position as shown in FIGS. 1 and 2C. Hence, there is a problem in that the semiconductor element 2 is not suitably mounted.
Specifically, in the case shown in FIG. 1, the circuit board 7 is inclined, which separates the right-most vias 8 and the solder bump 4. Thus, in the semiconductor device 1 having the conventional configuration, there is a problem in that poor electrical connection may be made between the semiconductor element 2 and the substrate 3, and reliability of the semiconductor device 1 is significantly degraded.
It should be noted that the circuit board 7 is conventionally made smaller than the opening 9 since a power supply electrode (terminal) and a ground electrode (terminal) provided in the semiconductor element 2 are generally arranged in the center portion of the semiconductor element 2. In other words, it is necessary to connect the capacitor forming part 12 formed in the circuit board 7 to the power supply electrode and the ground electrode of the semiconductor element 2. Thus, it is conceived that, in order to stabilize the power supply, which is the original object, arranging the circuit board 7 to face the center portion of the semiconductor element 2 where the power supply electrode and the ground electrode are provided will suffice, and it is unnecessary to further increase the size of the circuit board 7.